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This invention relates to priming mixtures for ammunition, particularlypriming mixtures of the non-corrosive type, such m x tures not onlyleaving no corrosive residue in the bore of the gun but apparentlw actually coating the bore of the gun an adherent protective film whichi'evw s, formation of rust even under the most ad =1- conditions.

It has long been recognized that otass um chlorate, the most commonlyuse oxidizer in priming mixtures, was responsible for the corrosion ofgun barrels which occurred subsequent to firing even though the barrelhad 35 been carefully cleaned and oiled. Potassium chlorate however, byreason of its high oxygen content, the ease with which it releases itsoxygen whenheated and its stabili in the presence of moisture wasremarka 1y well adapted for use as a priming mixture oxidizer, and thesecuring of a substitute therefor was a problem of great difiiculty. ynon-corrosive priming compositions have been tried but very few of thesehave been sufiiciently successful to be actually embodied in amanufacturers commercial product.

Recently, however, carefully prepared and proportioned compositions,using barium n1- trate as an oxidizer have been marketed wlthextraordinary success. In these compositions the content of mercuryfulminate is comparatively high on account of the necessity for reachingthe high temperature at which barium nitrate yields its oxygen. Primingmixtures containing a large amount of mercury fulminate are undesirablefor several reasons. Mercugy fulminate is comparatively expensive an thecost of the mixture is increased with an increase in the fulminatecontent. Of greater importance, however, is the fact that mercuryfulminateis of a poisonous nature and the preparation and handling ofmixtures containing a great deal as of fulminate are difiicult and maybe in- Application filed September as, 1923. Serial No. 805,129.

jur'ious to the workmen. Mercury fulminate is moreover, highlyexplosive, and must always he handled with extreme care.

The present invention comprises the discov ry of an explosive which maybe substituted for a part of the mercury fulminate in non-corrosivemixtures. The fulminate content being thus reduced, the mixture ischeapened and becomes much more safe-to make and handle.trinitroresorcinate, the normal lead salt of styphnic acidv(trinitroresorcinol) has been found to be most desirable.The'replacement of a partofthe mercury fulminate by leadtrinitroresorcinate not only makes the mixture more suitable forhandling "andloading but also serves to regulate the combustion of themixturein such a way as to eliminate certain irregularities which appearto be inevitable in non-corrosive mixtures containing mercury fulminateonly as an explosive.

Mercury fulminate detonates under the impact of the firing pin but thisaction being an instantaneous detonation, and not combustion, does notproduce a sustained flame.

For this purpose lead The result is that the temperature may not beraised sufiiciently to effect the proper reaction between the fuel andthe sluggish non corrosive oxidizer. Increasing the fulminate contentmerely serves to increase the force of this detonation, and not toappreciably increase the duration of the accompanying flame, andfurthermore the increase in the fulminate" content is productive ofpierced and broken cartridge heads due to the excessive momentarypressure brou ht about by the detonation. It has been ound accordin ly,that non-corrosive primers which depen on mercury fulminate alone as acombustion initiator are subject to certain irregularities ofperformance even when most carefully proportioned and mixed and loadedwith the utmost care. These varianevertheless undesirable andplacecertain restrictions upon the range of usefulness of such mixtures.

Lead trinitroresorcinate is less sensitive to blow and shock thanmercury fulminate but;

its reaction time is much longer, and is accompanied by well sustainedflame. This may be due to the fact that the decomposition of leadtrinitroresorcinate results in much more free carbon than thedecomposition of mercury fulminate. This carbon is burned with oxygensupplied by the priming mixture oxidizer with a hot and Well sustainedflame. Furthermore, the presence of the excess of nascent carbon servestoaccelerate gish barium nitrate, and the accompanying heat raises thetemperature to the point where oxygen is liberated for the combustionThese proportions, however, may be substantially varied. Good resultshave been secured with mixtures containing as little as 5% or as much as20% of lead trinitroresorcinate, the mercury fulminate content beingvaried accordingly, as between the range of 20% and 40%. Forexample,'the following is a very successful formula:

What is claimed is:

A noncorrosive priming mixture for wet loading into rim fire cartridgeshaving substantially the following composition:

Approximate per cent Mercury fulminate 30 Lead trinitroresorcinate 1OBarium nitrate 29 Lead sulphocyanate 1O Abrasive 20 -Binder 1 JAMES E.BURNS.

the release of oxygen by the otherwise slugj I Per cent. Mercuryfulminate 31.5 Lead trinitroresorcinate 5. 5 Barium nitrate 30.5 Leadsulphocyanate 10. 5. Abrasive 21 Binder; i 1 I The mixtures ofthisinvention are especially adapted for rim, fire cartridges, intowhich they are loaded in'a moist condition. A pelletof the moist primingmixture is dropped into the shell, and spun out into the shell rim by aspinning punch. The shell or powder case is comparatively short, and thepowder' lies in immediate contact with the priming mixture. Such rimfire cartridges require a priming mixture differing somewhat from thatused for center fire cartridges in which. the mixture may be loaded dryand is placed in aseparate-cup which communicates with.- the end of along powder case through a flash hole. The present invention is thoughtto constitute the first rim fire mixture containing mercury fulminateand lead trinitroresorcinate, and the appended. claims are to be broadlyconstrued.

